Square.



PATENTED NOV. 12,1907,

G. M. PRAUL.

SQUARE.

APPLICATION rum) AUG. 3, 190a.

[NI ENTOR UM 7128M 1 7a wZ By MW Al/orney UNITED STATES PATENT OFFICE.

CHARLES M. PRAUL, OF ATLANTIC CITY, NEW JERSEY, ASSIGNOR TO HENRY K.FORT, OF

' HADDONFIELD, NEW JERSEY SQUARE Specification of Letters Patent.

Patented Nov. 12, 1907.

Application filed August 3. 1906- Serial No. 329.032.

To all whom it may concern:

Be it known that I, CHARLES M. PRAUL, a citizen of the United States,residing at Atlantic City and State of New Jersey, have invented certainnew and useful Improvements in a Square, of which the following is aspecification.

Myinvention relates to improvements in squares such as used bycarpenters, masons, metal workers and other mechanics, and particularlyto squares having the two members or blades detachable.

The object of my invention is to provide means for readily locking theblades together so that they will be held together rigidly and at rightangles to each other; a further obj eet of my invention is to form thelocking device for the square so that the same will be flush with thesurface of the arms forming the square; a still further object of myinvention is to so construct the locking device that the blades may bequickly taken apart and put together by the fingers alone without theaid of other tools and so that it can be manufactured at a very lowcost. My invention may also be applied to Tsquares.

- Referring to the drawings :-Figure 1. is a plan view of the squareshowing my improved locking device; Fig. 2. is a side view of one of theblades shown in Fig. l. detached; Fig. 3. is a plan view of Fig. 2; Fig.4. is a cross section on lines 44 Fig. 3; Fig. 5. is a plan view of theother blade shown in Fig. 1. detached; Fig. ,6. is a side view of Fig.5; Fig. 7. is a plan view of a square showing a different form oflocking wedge.

In the drawings A andB represent the blades of a square. When used as aT square the wider blade A will form the head of the T square and theblade B will form the long blade. The blade or head A will be extendedas shown in dotted lines Fig. 1. when used as a T square. j

The blade B has a projecting tongue 0 of less thickness than the bladeand has beveled edges D. The blade 'A has formed therein a recess E of ashape cor- 40 responding to the tongue C. The recess E is of sufficientdepth to receive the tongue C and allow the surface of the same to beflush with the surface of the blade Af The recess E is provided withdove-tail edges which correspond to the beveled edges D of the tongue 0.The tongue 0 may be made wedge shape or its sides may be parallel but Iprefer to use the form shown in the drawings as it makes a tighterjoint.

A key orwedge F having beveled edges is fitted into a recess G formed nthe blade A. The said recess has dove-tail edges correspondingto theedges of the key F so as to hold the key from falling out of the recessG. The sides of the recess G are parallel as shown in Fig. 1. and aportion of the key F is cut on an angle to form a cam surface f. This isadapted to bear against the shoulder H on the tongue 0. The shoulder His formed by cutting a recess across the face of the tongue 0. When thekey F is forced into the recess of the tongue C the two blades A and Bwill be drawn tightly together and form a very rigid joint. The blade Bis provided with projecting corners I and I which fit under projectingcorners .T and J on the blade A and greatly strengthen the joint as wellas assuring a perfect right-angle joint.

Fig. 7. illustrates a different form of making the key F in which thesame is wedge shape. A screw K enters a slot L in the key to prevent thekey from falling out of the recess G when the key is moved to the largerend of the said recess. In the form shown in Fig. 1. the key F can onlybe removed by sliding it out of the end of the recess G which can onlybe done after removing the pin M.

By myimproved form of locking device the blades are securely heldtogether, the key will tighten the blades even after the parts havebecome worn and will always make a rigid right-angle joint. The bladescan be readily taken apart and put together without the use of tools andthe parts are all flush with the surface of the blades. And the wholecan be manufactured at a very low cost.

The tongue 0 or the key F may be made without the dove-tail edgeswithout departing from my invention but I prefer to use the form shownin the drawings as in this way the parts are more securely heldtogether.

Having thus described my invention I 'claim and desire to secure byLetters Patent:

1. The combination of a square having a blade, a tongue on said blade, ablade having a recess formed in the surface thereof conforming in shapewith said tongue, 21 key, said tongue and said latter blade havingformed therein a recess extending across the face of the same andadapted to receive said key.

2. The combination of a square having a blade, a tongue on said blade,said tongue having its side edges beveled, a blade having a recessformed in the surface thereof having dovetail edges to conform with saidtongue, a key, said tongue and said latter blade having formed therein arecess extending across the face of the same and adapted to receive saidkey.

3. The combination of a square having a blade, a tongue formed on thesame, said tongue having a recess formed across the face of the same, ablade having a recess formed therein to receive said tongue, said latterblade having a recess formed therein having dove-tail edges, a keyadapted to slide in the latter recess and lock the parts together,substantially as described.

4. The combination bf a square having a blade, a tongue formed on thesame, said tongue having a recess formedacross the face of the same, ablade having a recess formed therein to receive said tongue, said latterblade having a 10 recess formed therein having dove-tail edges, a keyhaving beveled edges adapted to slide in the latter recess, and said keybeing larger at one end than at its other end, substantially asdescribed.

In testimony whereof I aflix my signature in presence of two witnesses.

CHARLES M. PRAUL.

